The scale widget displays a slider in a trough. The trough represents a range of numeric values, and the slider position represents the current value. The scale can have an associated label, and it can display its current value next to the slider. The value of the scale can be used in three different ways:
Explicitly get and set the value with widget commands.
Associate the scale with a Tcl variable. The variable is kept in sync with the value of the scale, and changing the variable affects the scale.
Register a Tcl command to be executed after the scale value changes. You specify the initial part of the Tcl command, and the scale implementation adds the current value as another argument to the command.